DOUBLEDOS - Unprotect
Based on The Lone Victor's
routine.
The following instructions show you how to bypass the SoftGuard
copy protection scheme used on DOUBLEDOS version 1.00. This is the same
scheme used for FrameWork 1.10 and for Wordstar 2000 1.00. Wordstar
2000 version 1.10 does not use a copy protection scheme, while versions
1.00 of dBase III and FrameWork used ProLock. To unprotect Prolock disks
read the file PROLOCK.UNP.
First, using your valid, original DOUBLEDOS diskette, install it on
a fixed disk. Softguard hides three files in your root directory:
CML0200.HCL, VDF0200.VDW, and DOUBLEDO.EXE. It also copies DOUBLEDO.COM into
your chosen DOUBLEDOS directory. DOUBLEDO.EXE is the real DOUBLEDOS program,
encrypted. When you run DOUBLEDOS, the program DOUBLEDO.COM loads CML0200.HCL
high in memory and runs it. CML decrypts itself and reads VDF0200.VDW.
The VDF file contains some code and data from the fixed disk FAT at the
time of installation. By comparing the information in the VDF file with
the current FAT, CML can tell if the CML, VDF, and DOUBLEDO.EXE files are
in the same place on the disk where they were installed. If they have
moved, say from a backup & restore, then DOUBLEDOS will not run.
Second, un-hide the three files in the root directory. You can do
this with the programs ALTER.COM or FM.COM found on any BBS.
Make copies of the three files, and of DOUBLEDO.COM, into some other
directory.
Hide the three root files again using ALTER or FM.
Following the DOUBLEDOS instructions, UNINSTALL DOUBLEDOS. You can now
put away your original DOUBLEDOS diskette. We are done with it.
Next we will make some patches to CML0200.HCL to allow us to trace
through the code in DEBUG. These patches will keep it from killing our
interrupt vectors.
debug cml0200.hcl
e 3F9 2A.4A ; change the 2A to 4A
e 49D F6.16 ; if any of these numbers don't show up
e 506 E9.09 ; it's not working.
e A79 00.20 ;
e AE9 00.20 ;
e 73C 97 FA FA F4 F1 7E ; this is an encrypted call to 0:300
w ; write out the new CML file
q ; quit debug
Now copy your four saved files back into the root directory and
hide the CML0200.HCL, VDF0200.VDW, and DOUBLEDOS.EXE files using ALTER or FM.
We can now run DOUBLEDO.COM using DEBUG, trace just up to the point
where it has decrypted DOUBLEDO.EXE, then write that file out.
debug dOUBLEDO.COM
r ; write down the value of DS for use below.
a 0:300 ; we must assemble some code here
pop ax
cs:
mov [320],ax ; save return address
pop ax
cs:
mov [322],ax
push es ; set up stack the way we need it
mov ax,20
mov es,ax
mov ax,0
cs:
jmp far ptr [320] ; jump to our return address
g 406 ; now we can trace CML
t
g 177 ; this stuff just traces past some
g 1E9 ; encryption routines.
t
g 54E ; wait while reading VDF & FAT
g=559 569
g=571 857 ; DOUBLEDO.EXE has been decrypted
rBX ; length DOUBLEDO.EXE = 04800 bytes
:0 ; set BX to 0
rCX
:4800 ; set CX to 4800.
nDOUBLEDO ; name of file to write to
w XXXX:100 ; where XXXX is the value of DS that
; you wrote down at the begining.
q ; quit debug
Last, unhide and delete the three root files CML0200.HCL, VDF0200.VDW,
and DOUBLEDO.EXE. Delete DOUBLEDO.COM and rename DOUBLEDO to DOUBLEDO.EXE. This is the
real DOUBLEDOS program without any SoftGuard code or encryption. It requires
only the DOUBLGD2.PGM and DDCONFIG.SYS files to run.